Tissue stabilization and ablation devices and methods

ABSTRACT

Tissue stabilization and ablation devices and methods provide techniques for stabilizing and ablating body tissues during surgical ablation procedures. In many embodiments, for example, devices may be used in minimally invasive techniques for ablating epicardial tissue adjacent one or more pulmonary veins to treat atrial fibrillation. Tissue stabilization and ablation devices generally include a rigidifying bladder coupled with an ablation member. The devices may additionally include a tissue stabilizing bladder or means within the rigidifying bladder for enhancing tissue stabilization. The rigidifying bladder conforms to a tissue surface and then stiffens to help the device hold its shape and position and to stabilize the tissue. The ablation member is then used to ablate an area of tissue. Such cardiac stabilization and ablation devices and methods may be used to ablate one or more patterns on the epicardial surface of a heart to treat atrial fibrillation and/or other cardiac arrhythmias.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. patentapplication Ser. No. 09/268,556, filed Mar. 15, 1999, now U.S. Pat. No.6,607,479, which is a continuation-in-part of U.S. patent applicationSer. No. 09/042,853, filed Mar. 17, 1998, now U.S. Pat. No. 6,251,065B1, the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to medical devices and methods.More specifically, the invention relates to devices and methods forstabilizing and ablating body tissues, such as cardiac tissue, to treatvarious conditions, such as atrial fibillation.

Atrial fibrillation (AF) is a heart beat rhythm disorder in which theupper chambers of the heart known as the atria quiver rapidly, insteadof beating in a steady rhythm. This rapid quivering reduces the heart'sability to properly function as a pump. AF is characterized by circularwaves of electrical impulses that travel across the atria in acontinuous cycle. It is the most common clinical heart arrhythmia,affecting more than two million people in the United States and some sixmillion people worldwide.

Atrial fibrillation typically increases the risk of acquiring a numberof potentially deadly complications, including thrombo-embolic stroke,dilated cardiomyopathy and congestive heart failure. Quality of life isalso impaired by common AF symptoms such as palpitations, chest pain,dyspnea, fatigue and dizziness. People with AF have, on average, afive-fold increase in morbidity and a two-fold increase in mortalitycompared to people with normal sinus rhythm. One of every six strokes inthe U.S. (some 120,000 per year) occurs in patients with AF, and thecondition is responsible for one-third of all hospitalizations relatedto cardiac rhythm disturbances (over 360,000 per year), resulting inbillions of dollars in annual healthcare expenditures.

AF is the most common arrhythmia seen by physicians, and the prevalenceof AF is growing rapidly as the population ages. The likelihood ofdeveloping AF increases dramatically as people age; the disorder isfound in about 1% of the adult population as a whole, and in about 6% ofthose over age 60. By age 80, about 9% of people (one in 11) will haveAF. According to a recent statistical analysis, the prevalence of AF inthe U.S. will more than double by the year 2050, as the proportion ofelderly increases. A recent study called The Anticoagulation and RiskFactors in Atrial Fibrillation (ATRIA) study, published in the Spring of2001 in the Journal of the American Medical Association (JAMA), foundthat 2.3 million U.S. adults currently have AF and this number is likelyto increase over the next 50 years to more than 5.6 million, more thanhalf of whom will be age 80 or over.

As the prevalence of AF increases, so will the number of people whodevelop debilitating or life-threatening complications, such as stroke.According to Framingham Heart Study data, the stroke rate in AF patientsincreases from about 3% of those aged 50-59 to more than 7% of thoseaged 80 and over. AF is responsible up to 35% of the strokes that occurin people older than age 85.

Efforts to prevent stroke in AF patients have so far focused primarilyon the use of anticoagulant and antiplatelet drugs, such as warfarin andaspirin. Long-term warfarin therapy is recommended for all AF patientswith one or more stroke risk factors, including all patients over age75. Studies have shown, however, that warfarin tends to beunder-prescribed for AF. Despite the fact that warfarin reduces strokerisk by 60% or more, only 40% of patients age 65-74 and 20% of patientsover age 80 take the medication, and probably fewer than half are on thecorrect dosage. Patient compliance with warfarin is problematic, and thedrug requires vigilant blood monitoring to reduce the risk of bleedingcomplications.

Electrophysiologists classify AF by the “three Ps”: paroxysmal,persistent, or permanent. Paroxysmal AF—characterized by sporadic,usually self-limiting episodes lasting less than 48 hours—is the mostamenable to treatment, while persistent or permanent AF is much moreresistant to known therapies. Researchers now know that AF is aself-perpetuating disease and that abnormal atrial rhythms tend toinitiate or trigger more abnormal rhythms. Thus, the more episodes apatient experiences and the longer the episodes last, the less chance ofconverting the heart to a persistent normal rhythm, regardless of thetreatment method.

AF is characterized by circular waves of electrical impulses that travelacross the atria in a continuous cycle, causing the upper chambers ofthe heart to quiver rapidly. At least six different locations in theatria have been identified where these waves can circulate, a findingthat paved the way for maze-type ablation therapies. More recently,researchers have identified the pulmonary veins as perhaps the mostcommon area where AF-triggering foci reside. Technologies designed toisolate the pulmonary veins or ablate specific pulmonary foci appear tobe very promising and are the focus of much of the current research incatheter-based ablation techniques.

Currently available devices and methods, however, do not provide idealmeans for cardiac stabilization and ablation of epicardial tissue inadvantageous patterns for treating AF. Although many ablation devicesand stabilization devices are currently available, combiningstabilization and ablation features into one device to allow ablation ofepicardial tissue in a desired pattern on a beating heart has provenchallenging. Typically, therefore, current cardiac ablation proceduresfor AF treatment still require stopping the heart and using acardiopulmonary bypass apparatus.

Therefore, a need exists for devices and methods to enhance minimallyinvasive techniques for ablating cardiac tissue to treat AF. Preferably,such devices and methods would provide ablation in one or more patternson the epicardial surface of the heart, such as in a pattern adjacent toor surrounding one or more pulmonary veins. Also preferably, the devicesand methods would provide stabilization of the heart as well asablation, to allow for minimally invasive ablation procedures withoutcardiopulmonary bypass. At least some of these objectives will be met bythe present invention.

BRIEF SUMMARY OF THE INVENTION

Devices and methods of the present invention provide for stabilizationand ablation of a body tissue. In some embodiments, for example, devicesand methods are used to stabilize and ablate epicardial tissue to treatatrial fibrillation (AF). Stabilization/ablation devices generallyinclude a rigidifying bladder coupled with a tissue securing bladderhaving one or more ablation elements. In some embodiments, however,devices may include one bladder divided into rigidifying and tissuesecuring elements. Rigidifying and/or securing bladders may be coupledwith one or more engaging members for engaging a stabilization/ablationdevice with one or more positioners used for positioning the device on atissue. Generally, bladders and engaging members allow for positioningand securing of the device onto an area of tissue and for stabilizingthe tissue during an ablative procedure.

Ablation of tissue, such as epicardial tissue in a pattern around or inproximity to one or more pulmonary veins, may eliminate or ameliorateAF. Ablation of epicardial or other tissues in various other patternsmay have other beneficial effects. Generally, any suitable means fortissue ablation may be used in the present invention, such as but notlimited to transmission of radio frequency energy, cryogenic energy,microwave energy, laser energy or ultrasound energy. To enhance theefficacy of ablation procedures using the devices and methods of thepresent invention, various embodiments include one or more sensors fordetecting ablation of a tissue, cooling members for cooling a tissueand/or the ablation device, visualization means such as an and/or thelike.

In one aspect of the present invention, a method of stabilizing andablating body tissue includes contacting a tissue stabilizer having anon-rigid bladder with the tissue, securing the tissue stabilizer to thetissue, rigidifying the bladder, and applying ablation energy to atleast a portion of the tissue through the rigidified bladder. In someembodiments, rigidifying the bladder comprises applying a vacuum to thebladder, wherein the vacuum collapses the bladder to cause the bladderto rigidify. Optionally, the vacuum may be applied to the tissue throughat least one aperture in the bladder to enhance securing of the tissuestabilizer to the tissue. For example, the vacuum may be applied to thetissue through a separate tissue securing bladder coupled with therigidified bladder. Alternatively, the vacuum may be applied to thetissue through a tissue securing compartment in the rigidified bladder.

In many embodiments, the rigidifying bladder will further include atleast one port, a chamber within the bladder and in communication withthe port, and rigidifying structure disposed within the chamber. Therigidifying structure is generally configured to be substantiallyflexible when no suction is applied at the port and substantially rigidwhen suction is applied at the port.

As discussed further below, the tissue that is stabilized and ablatedmay be any suitable body tissue, of a human, animal, cadaver, or thelike. Frequently, the tissue will be heart tissue adjacent at least onepulmonary vein, as in the treatment of AF. For example, epicardialtissue near two pulmonary veins will often be stabilized and ablatedwith embodiments of the invention.

Contacting of the device with the tissue to be stabilized and ablatedmay be accomplished by any suitable means. In some embodiments, where aheart tissue is ablated, the heart may be accessed and contacted via aconventional surgical approach, such as via a median sternotomy. Inother embodiments, the device may be positioned for contact with hearttissue via minimally invasive means, such as by folding a flexibledevice and inserting it through a trocar sheath. Similarly, devices andmethods of the present invention may be used as part of any suitablecardiothoracic surgical procedure or cardiovascular intervention, suchas beating heart surgery or surgery involving cardiopulmonary bypass.

Ablating tissue with the ablation member may include any suitable meansof ablation. For example, various embodiments may include radiofrequency ablation, cryoablation, ultrasound energy ablation, laserablation and/or the like. Optionally, the ablation member may furtherinclude a partially retractable radio frequency coil, or other partiallyretractable apparatus for transmitting energy. In such embodiments, themethod will further include deploying the retractable radio frequencycoil or other apparatus to allow the ablation member to contactadditional tissue. For example, such a retractable apparatus may be usedwith a U-shaped device to allow the ablation member to encircle orsurround heart tissue around two pulmonary veins.

In yet other embodiments, the tissue stabilization/ablation devicefurther includes at least one sensor for sensing ablation of the tissue.In such embodiments, methods will include sensing, with the sensor, anamount of ablation of the tissue. This may be accomplished via one ormore sensing devices, such as thermal sensors, electrocardiogramsensors, radio frequency sensors, or the like, positioned adjacent theablation member. In some embodiments, sensors may be used to senseablation occurring at different parts of the ablation member. Typically,but not in all embodiments, sensors will comprise pairs of sensor, withone sensor in each pair transmitting a signal across an area to beablated and its paired sensor receiving the signal. Since ablated tissuewill generally transmit signal poorly, the pairs of signals can detectwhich areas of tissue have been ablated.

Optionally, the tissue stabilization/ablation device may include atleast one cooling member for decreasing heat generated by the ablationmember. In such embodiments, methods will include cooling the tissuestabilizer using the cooling member. For example, the cooling member mayinclude a hollow member through which a cooling fluid may be passed tocool an ablation member, adjacent tissue and/or the like. The hollowmember may take the form of a tubular member, a bladder or the like. Inother embodiments, a cooling member may comprise a series of fluidoutlet ports for allowing cooling fluid to be passed through a portionof the device to be cooled.

In another aspect of the invention, a device for stabilizing andablating tissue generally includes a flexible rigidifying bladder, atissue securing bladder and at least one ablation member. The flexiblebladder includes at least one chamber within the bladder, at least oneport in communication with the chamber, and rigidifying structuredisposed within the chamber, wherein evacuation of the chamber via theport causes the rigidifying bladder to rigidify. The tissue securingbladder is coupled with the flexible rigidifying bladder and isconfigured to contact the tissue and generate a suction force to enhancecontact of the device with the tissue. Finally, the ablation member iscoupled with the tissue securing bladder for ablating at least a portionof the tissue with which the tissue securing bladder is in contact.

Generally, the flexible rigidifying bladder, tissue securing bladder andablation member(s) may have any suitable shape, size or configuration,in two or three dimensions, for stabilizing and ablating tissue. Forexample, in some embodiments the tissue securing bladder comprises aflat U-shaped bladder for contacting heart tissue adjacent at least twopulmonary veins. The ablation member may also be a U-shaped member forablating tissue adjacent at least two pulmonary veins. In anotherembodiment, the tissue securing bladder may comprise a conically-shaped,elliptically-shaped or pyramidally-shaped member.

Typically, the tissue securing bladder includes at least one suctionhole for applying suction to enhance the contact of the bladder to thetissue. In some embodiments, the suction hole is configured to allow aportion of the tissue to be drawn into the hole when suction is applied.The ablation member may then be disposed about the at least one suctionhole, to allow ablation of the portion of tissue drawn into the suctionhole.

Generally, the ablation member may have any suitable configuration. Insome embodiments, for example, multiple ablation members may be used toablate a desired pattern on a tissue. In one embodiment, for example,the ablation members include a first linear ablation member forcontacting heart tissue between a left pulmonary vein and a rightpulmonary vein; a second linear ablation member for contacting hearttissue at a location approximating a line extending to theatrioventricular groove of a heart, and a third linear ablation memberfor contacting heart tissue on a left atrial appendage. In anotherembodiment, ablation member is configured to ablate tissue adjacent atleast one pulmonary vein. This tissue may include epicardial tissuewholly or partially surrounding or encircling two pulmonary veins, forexample. Any pattern of ablation is contemplated within the scope of thepresent invention.

Typically, the ablation member comprises an energy transmission member.The transmitted energy may be radio frequency energy, ultrasound energy,microwave energy, cryogenic energy or any other form of energy suitablefor ablation. For example, one or more radio frequency coils are oftenused as an ablation member. In other embodiments, however,thermoelectric chips may be used. In general, any suitable energytransmission device may be used as ablation members in the presentinvention.

Optionally, as mentioned above, the device may include one or moresensors for sensing ablation of the tissue. In some embodiments, forexample, such sensors sense an electrical depolarization in hearttissue. The sensors may generally include thermal sensors, electricalsensors, thermoelectric sensors, microchips, ultrasound sensors and/orthe like. In some embodiments, pairs of sensors may be positioned onopposite sides of an ablation member to sense activity of the ablationmember. In each pair, one sensor may send a signal toward an a secondsensor across an area of ablated tissue. Since a given form of energymay not travel across ablated tissue, the pair of sensors will detecteffective ablation when the energy is not transmitted across the tissue.

Also as mentioned above, devices of the present invention may include atleast one cooling member for decreasing heat generated by the ablationmember. For example, the cooling member may include a hollow tubularmember adjacent the ablation member and at least one port coupled withthe hollow member for allowing introduction of one or more coolingfluids into the hollow member. Some embodiments include an inlet portfor allowing the introduction of one or more cooling fluids and anoutlet port for allowing egress of the one or more cooling fluids fromthe hollow tubular member.

Devices of the present invention may be introduced to an area fortreatment and may be positioned by any suitable means. For example,devices of the invention will typically include one or more positioningdevices coupled with the rigidifying bladder and/or the tissue securingbladder. A positioning device may include a plate or foot, which may becoupled with an arm to position the device. Such a plate or foot may bepositioned between the bladders, outside the bladders or at any othersuitable location. In some embodiments, devices will be sufficientlyflexible to be rolled up and inserted to a treatment site via a trocar.In such embodiments, positioning members may be disposed on the outsideof one of the bladders such that the positioning members are couplablewith a positioning arm or similar device.

In another aspect of the present invention, a device for stabilizing andablating tissue includes a flexible rigidifying bladder and at least oneablation member coupled with the flexible rigidifying bladder forablating at least a portion of the tissue. The flexible bladder includesa chamber, at least one port in communication with the chamber, at leastone tissue securing means in communication with the chamber, at leastone mesh-like member for dividing the chamber into multiplesub-chambers, and rigidifying structure disposed within at least onesub-chamber. In this embodiment, application of suction to the chambervia the port causes the rigidifying structure to rigidify the bladderand causes the tissue securing means to adhere to the tissue. In someembodiments, the tissue securing means comprises one or more suctionmembers. Generally, any of the variations and optional featuresdescribed above may be applied to this embodiment of the invention.

It should be understood that devices and methods of the presentinvention may suitably include any additional apparatus to enhanceminimally invasive tissue stabilization and ablation. For example,devices may include one or more endoscopic devices for enhancingvisualization, one or more elongate shafts or other positioning arms forplacing a device, one or more trocar sheaths for introducing a flexibledevice and/or the like. All such embodiments and variations arecontemplated within the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective, top-surface view of an exemplary cardiacstabilization and ablation device in accordance with one embodiment ofthe present invention.

FIGS. 2A-E are perspective, bottom-surface views of various embodimentsof a cardiac stabilization and ablation device as in FIG. 1.

FIG. 3A is a cross-sectional view of the stabilization componentcardiacstabilization and ablation device taken along line 3-3 of FIG. 1,illustrating a rigidifying bladder without applied suction.

FIG. 3A′ is view similar to that of FIG. 3A, illustrating therigidifying bladder with applied suction.

FIG. 3B is a cross-sectional view of the cardiac stabilization andablation device taken along line 3-3 of FIG. 1, illustrating analternative embodiment of the stabilizer.

FIG. 3C is a cross-sectional view of the cardiac stabilization andablation device taken along line 3-3 of FIG. 1, illustrating yet anotheralternative embodiment of the stabilizer.

FIG. 4 is a cross-sectional view of the cardiac stabilization andablation device taken along line 4-4 of FIG. 3C, without the ablationmember shown.

FIG. 5 is a cross-sectional view of the cardiac stabilization andablation device taken along line 5-5 of FIG. 1, without the ablationmember shown.

FIG. 5A is an enlarged fragmentary cross-sectional view of a rigid plateand rigidifying structure according to one embodiment of the invention.

FIG. 5B is a cross-sectional view of a rigidifying structure accordingto one embodiment of the invention.

FIG. 6 is a plan view illustrating an exemplary embodiment of anengaging structure of the invention.

FIG. 7 is a plan view illustrating an alternative embodiment of anengaging structure of the invention.

FIG. 8 is a cross-sectional view of the engaging structure taken alongline 8-8 of FIG. 7.

FIG. 9 is a cross-sectional view of the engaging structure taken alongline 9-9 of FIG. 7.

FIG. 10 is a schematic view of a cardiac stabilization and ablationdevice according to one embodiment of the present invention in useduring a cardiac ablation procedure on a heart.

FIG. 11 is a perspective view of an embodiment of a cardiacstabilization and ablation device of the present invention which may beinserted into a body through a trocar sheath.

FIG. 12A is a perspective view of another embodiment of a cardiacstabilization and ablation device of the present invention which may beinserted into a body through a trocar sheath.

FIG. 12B is a cross-sectional side view of the device in FIG. 12B.

FIGS. 13A-B are perspective views of still another embodiment of acardiac stabilization and ablation device of the present invention whichmay be inserted into a body through a trocar sheath.

DETAILED DESCRIPTION OF THE INVENTION

Devices and methods of the present invention generally provide forstabilization and ablation of a body tissue. Various embodiments areoften described below in the context of stabilizing and ablatingepicardial tissue on a human heart in proximity to one or more pulmonaryveins for treating atrial fibrillation. It should be understood,however, that these or other embodiments may be used for stabilizationand/or ablation of any other suitable human body tissues, may be used ina veterinary, research or other context, may be employed to treat a widevariety of other conditions, and/or the like, without departing from thescope of the present invention.

Typically, devices of the present invention include a rigidifying tissuestabilization device coupled with one or more ablation members. Forexample, a tissue stabilization device may include a rigidifying bladdercoupled with a tissue securing bladder. Some embodiments also includeadditional features, such as but not limited to sensing members, coolingmembers and/or engaging members for coupling the device with apositioner. Methods generally provide for contacting a device with atissue, stabilizing the tissue with the device and ablating the tissue.In various embodiments, tissue may be contacted and ablated in anysuitable pattern, configuration and/or geometry and with any suitabletype or power of ablation device. Although specific exemplary devicesand methods are described in detail below and in the appended drawingfigures, these examples are intended for illustrative purposes only andshould not limit the scope of the invention as set forth in the claims.

Referring now to FIGS. 1 and 2A-E, a cardiac stabilization and ablationdevice 10 according to one embodiment of the present invention is shown.One example of an apparatus for stabilizing tissue is described in U.S.Pat. No. 6,251,065, issued to Kochamba et al., of which the presentapplication is a continuation-in-part.

FIG. 1 is a top, or superior perspective, view of stabilization/ablationdevice 10, many features of which are described more fully below and/orin U.S. Pat. No. 6,251,065. Generally, stabilization/ablation device 10includes a tissue attaching bladder 12 for contacting device 10 with abody tissue, a rigidifying bladder 14 coupled with tissue attachingbladder 12, and an ablation member 13 (FIGS. 2A-E) coupled with tissueattaching bladder 12 for ablating the body tissue. These elements aredescribed in further detail below.

Many embodiments of device 10 also include one or more engaging membersfor enabling the device to be removably coupled with a positioningdevice and/or for enhancing the contact of device 10 with a tissue to beablated. For example, some embodiments include a rigid plate 52 coupledwith one or more engaging structures 54 for engaging with a positioningarm or other positioning device. In FIG. 1, for example, engagingstructure 54 includes a post 60 and a ball 58 coupled with one end ofthe post. As described further below, other embodiments do not include arigid plate, allowing device 10 to be predominantly flexible when not inits rigidified state. Such a flexible device 10 may be manipulated, suchas by folding, to enable the device to be introduced to a surgical sitevia a minimally invasive introducer or similar means. These optionalelements are described in more detail below.

It should be emphasized that although shown as a U-shaped, relativelyflat device in FIGS. 1, 2A-E and many of the following figures, device10 may have any suitable shape, size and configuration, in two or threedimensions, for stabilizing and ablating tissue. In various embodiments,for example, device 10 may be round, square, ovoid, curved, circular,cylindrical, linear, elongate, conical or the like. Additionally,attaching bladder 12 may have a different size or shape than rigidifyingbladder 14 in some embodiments. In fact, attaching bladder 12,rigidifying bladder 14 and ablation member 13 may be given any suitableshapes, sizes or combination of shapes and sizes, without departing fromthe scope of the present invention.

In some embodiments, as shown in FIG. 1, device 10 further includes oneor more hinges 19, each with or without a hinge actuation member 17.Hinge 19 may allow the shape of device 10 to be adjusted, for example toconform to a desired ablation pattern at a treatment site. Actuationmember 17 may be used to activate or loosen hinge 19. For example,device 10 may be adjusted via hinge to close the open portion at the topof the U of device 10, such as when it desired to ablate tissueencircling a structure. In other embodiments, two or more hinges 19 maybe disposed on device 10 at various locations to allow furtheradjustment of device 10. Just as with device 10 as a whole, hinges 19 onand adjustments to device 10 may assume any suitable configuration.

Referring now to FIG. 2A, a bottom, or inferior perspective, of device10 is shown. Typically, one or more ablation members 13 and one or moresensors 15 are coupled with tissue attaching bladder 12 to enableablation of tissue contacted with attaching bladder 12 and sensing ofablation by sensors 15. In some embodiments, ablation member 13 andsensors 15 are positioned on the surface of attaching bladder 12, whilein other embodiments they may be embedded in attaching bladder 12 orotherwise coupled therewith.

In many embodiments, stabilization/ablation device 10 is largelyflexible and conformable to the shape or anatomical topography of aparticular piece or section of tissue, such as the epicardium of theleft or right ventricle or left or right atria of a heart. Thus,ablation device 10 may be flexibly placed in contact with a tissuesurface in a substantially atraumatic manner and then secured to thetissue via tissue attaching bladder 12, for example through the use ofsuction. Once ablation device 10 is conformed and secured to a tissuesurface, it may then be rigidified via rigidifying bladder 14 tomaintain a desired shape. In some embodiments, for example, rigidifyingbladder 14 may actuated by applying suction. Once ablation device 10 isin place on a tissue, ablation member 13 may be activated to ablate thetissue. Each of these features of the present invention will bedescribed in detail below.

Ablation member 13 is generally configured for conveying ablative energyfrom an energy source to a tissue. In various embodiments, such ablativeenergy may include radio frequency (RF) energy, ultrasonic energy,microwave energy, cryoablative energy, or any other suitable source ofenergy. In some embodiments, in fact, ablation member 13 may include anapparatus for delivering one or more ablative drugs or other chemicalcompounds to a tissue. Therefore, although much of the followingdescription focuses on an embodiment including an RF coil ablationmember 13, this example should not be interpreted to narrow the scope ofthe invention in any way. Any suitable source of energy for ablationmember 13 may be used.

Furthermore, ablation member 13 may have any suitable configuration,shape or the like. In some embodiments, as in FIG. 2A, ablation member13 is a single U-shaped RF coil. In other embodiments, ablation member13 comprises more than one coil or other ablation device. For example,in one embodiment ablation member 13 may include one or more RF coils,each formed in a straight, curved, or shaped line. Multiple coils may beused to ablate various patterns on various tissue surfaces, such as whencreating various patterns on epicardial surfaces of hearts to treat AF.In an embodiment shown in FIG. 2E, for example, three linear RF coilsmay be used to ablate epicardial tissue. A first coil 92 ablates in aline running between a left pulmonary vein and a right pulmonary vein, asecond coil 94 ablates in a line extending to the atrioventriculargroove of the heart, and a third coil 96 ablates in a line extending tothe left atrial appendage. As demonstrated by this embodiment, two ormore coils or other ablation members may overlap. In other embodiments,linear coils may be used to extend ablation patterns to the right sideof the heart, to the coronary sinus, to the superior or inferior venacava, to the tricuspid valve annulus, to the right atrial appendage,and/or the like. In another embodiment, linear coils may be used inaddition to RF coils which partially or wholly surround the pulmonaryveins on one or more sides of the heart. In another embodiment, ablationmember 13 has a circular configuration to ablate in a pattern around astructure.

Other energy sources may be used for ablation. For example, as shown inFIG. 2D, multiple thermoelectric chips 82 may be used as ablationmembers 13 to transmit cryogenic energy. Such chips 82 may be arranged,for example, in a series or array to ablate tissue in a desired pattern.

Referring now to FIG. 2B, ablation member 13 may also include aretractable coil 21. Retractable coil 21 may be retracted into a coilhousing 27 and may be released by activation of a button or otherreleasing device (not shown). In some embodiments, for example as inFIG. 2B, such retractable coil 21 may be released to cross the open endof a U-shaped ablation/stabilization device 10. This would allow forablation in a pattern encircling one or more structures. For example,tissue may be ablated in a pattern encircling one or more pulmonaryveins using such an embodiment.

It should be apparent that many configurations, dimensions, shapes andcombinations of ablation apparatus may be incorporated into ablationmember 13 without departing from the scope of the present invention. Forexample, in one embodiment, ablation member 13 may be formed in aU-shaped, semicircular, circular, or similar configuration to ablate anepicardial area adjacent to and/or around one or more pulmonary veins ona heart. In one embodiment of a U-shaped, RF coil ablation member 13,the depth of the internal surface of the U may measure between about 2.5and about 5.0 inches, and more preferably between about 3.0 and about4.0 inches, and the width of the internal surface of the U may measurebetween about 0.25 and about 2.0 inches, and more preferably betweenabout 0.5 and about 1.5 inches.

With reference now to FIG. 2C, in yet another embodiment ofablation/stabilization device 10, ablation member 13 may be configuredas a bipolar RF device. As shown in FIG. 2 c, such a bipolar ablationmember 13 typically includes two ablation members 13. These bipolarablation members 13 may be aligned towards the internal and externalcurvatures of a U-shaped device 10 or in any other suitableconfiguration to provide bipolar ablation.

As stated briefly above, ablation member 13 as in any of the embodimentsshown in FIGS. 2A-C and/or described above may use any suitable energysource and may be coupled with an energy source in any suitable manner.Thus, energy used to ablate tissue may include, but is not limited to,RF, microwave, ultrasound and cryogenic energy. Connection apparatus andenergy sources are not shown in the drawing figures, but it will beapparent to those skilled in the art that any suitable energy source maybe coupled with device 10 by any suitable means. Additionally, invarious embodiments energy source may be external and coupled viawiring, internal to device 10, external and coupled remotely, orconfigured in any other suitable way to provide energy to device 10.

Various embodiments of stabilization/ablation device 10 may furtherinclude one or more cooling members for cooling ablation member 13,other portions of device 10 and/or contacted tissue. For clarity, suchcooling members are not shown in the drawing figures. However, a coolantinlet port 23 and coolant outlet port 31 are shown in FIGS. 2A-C. Manyembodiments of device 10 include one or more cooling members and most ofthose embodiments use one or more coolant fluids to achieve cooling ofablation member 13. The cooling member (or members), for example, mayinclude a hollow apparatus positioned in close proximity to ablationmember 13, either on one side or on both sides of ablation member 13.The hollow apparatus may comprise, for example, a tubular member, abladder or the like. A cooling fluid, such as saline, water, or othersuitable fluid may be infused into the hollow apparatus via coolantinlet port 23, allowed to circulate through the hollow cooling memberand then allowed to exit the cooling member via coolant outlet port 31.

Other embodiments may use multiple irrigation or outlet ports to coolablated tissue and/or device 10. Outlet ports may comprise multiplesmall holes in device 10, disposed around an ablation member or in anyother suitable configuration, allowing fluid to be passed through theholes to cool tissue or the device itself. Providing circulation of acooling fluid in close proximity to ablation member 13 in such a mannerwill typically decrease both the impedance and the temperature ofablation member 13 to increase efficiency and prevent unwantedoverheating. Generally, cooling members may have any suitable shapes,sizes and configurations and may use any suitable means for cooling. Forexample, some cooling members may encircle ablation member 10, some mayuse coolants or cooling mechanisms other than circulation of a fluid,and/or the like.

Referring to FIGS. 2A-B, various embodiments of ablation device 10 mayinclude one or more sensors 15 for sensing ablation by ablation member13. For example, sensors 15 may measure heat generated by ablationmember 13, may sense heat delivered to a contacted tissue, may senseelectrical or other energy potentials, and/or may use any other suitablemeans for sensing ablation. In some embodiments, for example, sensors 15detect RF current, impedance and/or the like. Sensors 15 may bepositioned in pairs, each member of a pair being positioned on oppositesides of ablation member 13. RF energy may be transmitted to differentportions of ablation member 13 through different RF channels and a pairof sensors 15 may accompany each different portion of ablation member13. Each pair of sensors 15 may then measure ablation from a portion ofablation member 13 and measurements from pairs of sensors 15 can becompared to determine whether certain portions of ablation member 13 areablating at a higher current, have a higher impedance, and/or the like,compared to other portions of ablating member 13. In such an embodiment,one sensor from each pair of sensors 15 may send a signal to itsaccompanying sensor across ablation member 13 and its accompanyingsensor 15 may act as a receiver. Transmitted energy from a sendingsensor 15 may not typically reach its paired sensor 15 across ablatedtissue, since ablated tissue will not typically transmit energyefficiently. Thus, a pair of sensors 15 may detect ablation in tissue.Sent and received signals may be processed by a microprocessor (notshown), which may either be built into device 10 or be disposed apartfrom device 10.

It should be apparent that any type, combination or configuration ofsensors may be used to sense ablation in device 10. Thus, individualsensors 15 rather than pairs are contemplated, as well as sensorsdistributed in any suitable pattern in or on device 10. Furthermore, anytype of apparatus suitable for sensing transmission of energy may beused. Therefore, sensors 15 of the present invention are not limited tothe pairs of RF sensors described above. Additionally, any suitablemeans for sending and receiving signals to and from sensors 15 may beused. In one embodiment, for example, a microprocessor chip is embeddedwithin device to send and receive signals to and from sensors 15. Inother embodiments, sensors 15 may each separately send and receivesignals to a microprocessor separate from device.

Referring now to FIG. 2C, yet another embodiment ofstabilization/ablation device 10 includes one or more tissue ports 25.Tissue port 25 is generally a concavity or trough of any shape,including for example a conical shape, on the surface of attachingbladder 12 which may or may not extend into a concavity on rigidifyingbladder 14. In one embodiment, one or more tissue port 25 may beconfigured to draw tissue toward suction openings 20 disposed withinport 25. One or more components of device 10 described above and below,such as ablation member 13, sensors 15, cooling members, suctioningdevices and/or the like may be positioned in tissue ports 25. Generally,placing one or more concave tissue ports 25 on attaching member 12 mayenhance attachment of attaching member 12, and therefore of device 10,to tissue. Tissue ports 25 may thus enhance efficiency of stabilizationand/or ablation by device 10.

With reference to FIG. 3A, attaching bladder 12 and rigidifying bladder14 are shown in cross section. In one embodiment, attaching bladder 12has a port 16 leading into an inner chamber 18 in which a plurality ofopenings 20 are formed. Attaching bladder 12 is substantially flexibleand configured so that openings 20 apply suction when suction is appliedat port 16. Rigidifying bladder 14 has a port 22 leading into an innerchamber 24 in which rigidifying structure 26 is disposed. A portion ofrigidifying structure 26 may be attached to bladder 14, and a portion ofthe rigidifying structure may be unattached or free floating.Free-floating rigidifying structure is exemplified in the figures bysubstantially spherical beads or balls, although any structureconfigured in accordance with the principles of the present inventionmay be utilized. In addition, rigidifying structure 26 may be configuredas a mesh-like sheet or as a corrugated sheet of material made from, forexample, nylon implanted or impregnated with silicone. At least aportion of the mesh-like or corrugated sheet may be attached torigidifying bladder 14. (The dimensions of the components ofstabilization/ablation device 10 in the drawings, such as the thicknessof the walls of bladders 12 and 14 are exaggerated for illustrativepurposes.)

With reference to FIGS. 3A and 3A′, rigidifying bladder 14 is configuredto be substantially flexible when suction is not applied at port 22,which is shown in FIG. 3A, and substantially rigid when suction isapplied at port 22, which is shown in FIG. 3A′. As shown in FIG. 3A,inner chamber 24 has an ambient volume which provides space in whichportions of rigidifying structure 26 may move with respect to eachother, allowing bladder 14 to bend and flex. However, when suction isapplied at port 22, negative pressure or a vacuum is induced withininner chamber 24, causing rigidifying bladder 14 to collapse uponitself, as shown in FIG. 3A′. Inner chamber 24 now has a collapsedvolume which is less than the ambient volume, and the space amongrigidifying structure 26 is substantially reduced, thereby increasingthe density of the rigidifying structure. Accordingly, individualportions of rigidifying structure 26 are urged together under pneumaticforce and resist relative movement with respect to each other. As shownin the drawings, structures such as free-floating beads engage withspaces formed between attached beads to resist lateral movement relativeto each other. If rigidifying structure 26 is configured as a mesh, thenfree-floating beans partially lodge within openings in the mesh. Withthe individual portions of rigidifying structure 26 urged together undervacuum to resist relative movement, collapsed rigidifying bladder 14 issubstantially inflexible, resists bending, and retains a stiffenedposition.

Rigidifying bladder 14 may be manufactured using any suitable materialor combination of materials. In one embodiment, for example, rigidifyingbladder 14 may be comprised of silicone impregnated with nylon.Rigidifying bladder 14 may be include natural fibers such as cotton(e.g., canvas) or metallic fibers such as stainless-steel mesh toprovide durability. Alternatively, rigidifying bladder 14 or othercomponents of device 10 may be made from substantially resilientmaterial, such as certain silicones, so as to stretch under sufficientforce. In addition, rather than pneumatic evacuation of rigidifyingbladder 14, fluids other than air, such as hydraulics may be used.

In this regard, a surgeon may apply and conform stabilization/ablationdevice 10 to tissue so that preferably a majority of openings 20 contactor are incident on the tissue. Suction may be applied at port 16,causing suction to be applied at the openings 20 and thereby attachingstabilization/ablation device 10 to the tissue. Suction may then beapplied at port 22 to stiffen or rigidify device 10, causing the deviceto maintain a desired position and configuration on the tissue. Inapplying device 10 to tissue in this matter, the surgeon may manipulatethe tissue as desired by manipulating the device because the tissue isheld or secured by device 10. Accordingly, the secured tissue moves whendevice 10 moves or maintains a stabilized position when device 10 ismotionless or anchored.

An alternative embodiment of device 10 is illustrated in FIG. 3B. Inthis embodiment, tissue attaching bladder 12 is configured so that innerchamber 18 is divided into a plurality of cells 28 which are connectedby a plurality of air passages 30 formed through dividing walls 32. Eachcell 28 may be elongate in shape, extending substantially from one sideof attaching bladder 12 to the other. Accordingly, each cell 28 mayinclude a number of openings 20 disposed in a row along an extentthereof, such as illustrated in FIGS. 2 a-c.

Also illustrated in FIG. 3B, rigidifying bladder 14 is configured sothat inner chamber 24 is divided into a plurality of cells 34 which areconnected by a plurality of air passages 36 formed through dividingwalls 38. Each cell 34 of rigidifying bladder 14 may be elongate inshape, extending substantially from one side of bladder 14 to the other.Each cell 34 includes rigidifying structure 26 which may be disposedeither attached to an inner wall of bladder 14 and/or dividing walls 38,free floating, or in a combination of both as shown in FIG. 3B.Free-floating rigidifying structure 26 may include spherical balls whichare dimensioned to be larger than air passages 36 to prevent passage ofthe balls through passages 36, as shown in FIG. 3B.

Another alternative embodiment of the tissue stabilizer of the presentinvention is illustrated in FIGS. 3C and 4. Rather than attachingbladders 12 and 14 in a substantially coplanar and coextensiverelationship as shown in FIGS. 3A and 3B, attaching bladder 12 isimbedded within rigidifying bladder 14 in device 10 shown in FIGS. 3Cand 4. In this embodiment, attaching bladder 12 includes a plurality ofbranching arms 40 which extend from a central channel 42. Each arm 40provides a pneumatic conduit to a number of the openings 20 of attachingbladder 12, thereby providing communication for each opening 20 to port16 via the inner chamber 18. Rigidifying bladder 14 exemplified in FIGS.3C and 4 may include an inner wall 44 which separates the inner chamber24 into two layers or sections. Wall 44 includes at least one airpassage 46 so that each section of chamber 24 is in pneumaticcommunication with port 22. Rigidifying structure 26 may includeattached as well as free-floating structure analogous to that describedabove. Although a single inner wall 44 is illustrated, rigidifyingbladder 14 may include a plurality of walls 44 to separate inner chamber24 into a plurality of sections or layers.

With continued reference to FIGS. 3C and 4, one embodiment of theinvention includes a combined bladder that has both rigidifying elementsand tissue stabilizing elements. Such an embodiment, similar to thatjust described above, has one common chamber that is divided into one ormore rigidifying sub-chambers and one or more tissue stabilizingsub-chambers by one or more pieces of mesh-like material. The mesh holdsrigidifying structure within the rigidifying sub-chambers. Allsub-chambers are in fluid communication, due to the mesh, so that whensuction is applied at a common port (as if port 22 and port 16 werecombined in FIG. 3C), the rigidifying sub-chambers rigidify and thetissue securing sub-chambers secure tissue. For example, the tissuesecuring sub-chambers may be in fluid communication with one or moresuction holes for securing tissue.

With reference now to FIGS. 1 and 5, stabilization/ablation device 10 ofthe present invention may also include a retaining structure 50 forengaging with external support apparatus. Retaining structure 50 mayinclude one or more substantially rigid plates 52 and one or moreengaging members 54. Plate 52 may be attached to either or both ofbladders 12 or 14 with, for example, adhesive, suture or suture-likematerial, or any other suitable coupling apparatus. (Components ofbladders 12 and 14 as described above are not shown in FIG. 5 forclarity.) Plate 52 may include a window 56 which provides a surgeonaccess to a surgical site on the tissue to which device 10 is attached.In the embodiment illustrated in the drawings, ablation device 10 andplate 52 have U-shape configurations, thereby defining window 56.

Although illustrated as a three-sided opening, window 56 may be foursided, that is, enclosed on all four sides. In addition, window 56 maybe curvilinear (rather than rectilinear as shown) and may be offset froma medial axis of the tissue stabilizer (rather than centered as shown).Ablation device 10 may be configured so that window 56 is wider at a topsurface of the device and narrower at a bottom surface of the device, orvice versa. In addition, multiple windows 56 may be formed in the tissuestabilizer. In a multiple window embodiment, windows 56 may function asa vent for promoting or facilitating air circulation, which will bediscussed in reference to alternative embodiments of the inventiondescribed below. In other embodiments, no window may be included. Forexample, many embodiments of device may be used for predominantlyablation only procedures, so that surgeon access to tissue through awindow in device 10 is not required.

Referencing FIG. 5A, the junction of rigid plate 52 and the bladders(either or both of bladders 12 and 14) may be configured at astress-reducing section 57. For example, rigidifying bladder 14 mayinclude rigidifying structure 26′ configured as a flexible nylon mesh,and plate 52 may be made from a substantially rigid nylon, with section57 being defined as an integral transition therebetween. Stress-reducingsection 57 is more resilient than rigid plate 52 but less resilient thanmesh 26′, thereby allowing the mesh to flex with respect to the plate.

In various embodiments, engaging structure 54 may be configured as aball 58 disposed on a post 60, with the post being attached to plate 52and projecting away from bladders 12 and 14. As shown in the drawings,engaging structure 54 includes a pair of balls 58 and posts 60. Balls 58are configured to releasably engage with complement external supportstructure, such as quick-release sockets with by a single flip leveroperated with one hand as known in the art, which will be discussed inmore detail below. Referring to FIG. 6, engaging structure 54 mayinclude a plurality ball-and-post structures (58 and 60) arranged ontissue stabilizer 10. The plural balls 58 may be configured so thatexternal support structure engages with at least two of the balls 58simultaneously. As such, stabilization/ablation device 10 is retained ina substantially rigid manner in all dimensions.

An alternative embodiment of the engaging structure of the presentinvention is illustrated in FIGS. 7, 8, and 9. Components of thealternative engaging structure 54′ analogous to those shown in FIGS. 1and 5 are referenced with like numerals with the addition of a prime(′). Exemplary engaging structure 54′ may include a cross bar 62extending between a respective pair of posts 60′ connected to rigidplate 52′. As shown in the drawings, a pair of cross bars 62 may beused. Each cross bar 62 is substantially rigid and provides an extendedstructure to which external support apparatus may be easily attached.When attached, ablation device 10 is pivotal only about a single axis,that is, the axis of the cross bar which is engaged with externalstructure. As particularly shown in FIG. 8, each cross bar 62 may have apolygonal cross section, for example, a hexagon.

Still further embodiments of retaining structures 50 of the presentinvention are shown in FIGS. 12A-B and 13A-B. FIGS. 12A and 12Billustrate an embodiment including two engaging structures 54 disposedat corners of device 10. Such engaging structures 54 may be coupled withtwo separate rigid plates 52, rather than one rigid plate 52. Multiplerigid plates 52 may allow device 10 to be manipulated more freely andperhaps even rolled up cylindrically and introduced to a treatment sitevia a trocar sheath (FIG. 11).

In FIGS. 13A and 13B, device 10 is shown with multiple externalretaining structures 50′. External retaining structures 50′ may be usedwhen a flexible device 10 is desired, for example when device 10 isintroduced in a folded or cylindrical form via a trocar sheath. Such anembodiment would typically not include a rigid plate and would be fullyflexible. Once positioned on or near a site for treatment of a tissue,device 10 may be coupled, via external retaining structures 50′, to oneor more positioning devices 64, such as positioning arms. Positioningdevices 64 could then be used to place device 10 in a desired positionfor ablation and could be decoupled from device 10 after use.

FIG. 10 illustrates an exemplary device 10 as it might be used on aheart 70 to perform a surgical ablation procedure. Anatomical featuresof heart 70 shown in FIG. 10 include right superior pulmonary vein 72,right inferior pulmonary vein 74, left superior pulmonary vein 73, leftinferior pulmonary vein 75 and aorta 82. Device 10 is shown in aposition to stabilize and ablate cardiac tissue adjacent right superiorpulmonary vein 72 and right inferior pulmonary vein 74. As alreadydiscussed, many other configurations and ablation patterns arecontemplated within the scope of the present invention.

To perform an ablation procedure on the heart, for example to treatatrial fibrillation, it is advantageous to have a stabilized heart 70.This may be accomplished by placing the patient on a heart-lung machineand stopping the heart from beating with cardioplegia. Alternatively,however, and through use of stabilization/ablation device 10, ablationmay be performed on a beating heart without the use of a heart-lungmachine.

To advance stabilization/ablation device 10 to an area for positioningand using device 10, access to the heart 70 is first achieved, such asthrough a medial sternotomy or thoracotomy, which may also involve aretractor. In some embodiments, and with reference now to FIG. 11,access may also be provided in a minimally invasive manner, such asintercostally through a trocar sheath 67 or a “mini” thoracotomy.

With reference again to FIG. 10, device 10 is typically applied to theheart 70 to stabilize the heart 70, thereby providing a stable operatingplatform for ablation of cardiac tissue. Ports 16 and 22 are connectedto a source for suction, such as wall suction 90. Device 10 may includea pair of valves 92 and 94 for regulating the suction between the wallsuction. 90 and ports 16 and 22, respectively. Device 10 may then bepositioned on the epicardium of the heart 70 in a position to provide adesired ablation pattern. When in a desired position for ablation,suction may be applied at port 16 of the attaching bladder 12 by, forexample, actuating valve 92, thereby attaching or securing device 10 tothe epicardium of heart 70.

The suction applied to port 16 is at a level which minimizes orsubstantially prevents trauma to the epicardium. Depending upon theconfiguration of attaching bladder 12, such as the size and/or number ofopenings 20, the level of applied suction may range from, for example,about 50 millimeters of mercury (mm Hg) to about 150 mm Hg. Thispressure range may be at the lower end of the scale if a relativelylarge number of openings 20 is provided and at the higher end of thescale if a relatively small number of openings 20 is provided.

The applied suction may attach stabilization/ablation device 10 to heart70 with a level of force which allows device 10 to be moved or slidacross the tissue under hand pressure. This feature facilitates thepositioning of device 10 to a desired location. It also enables flexibledevice 10 to be contoured to the anatomical topography of heart 70,providing optimal contact or incidence of the openings 20 on the surfaceof the epicardium. Thus, device 10 may conform to a surface of heart,such as epicardium overlying the left atrium, inferior vena cava andright atrium, as shown approximately in FIG. 10, much like a patch,substantially “wrapping” around a portion thereof. The U-shapeconfiguration of device 10 allows a surgeon to place a hand on thedevice with his or her fingers straddling window 56, which ergonomicallyfacilitates the positioning and contouring thereof. Only one hand istypically needed to position device 10 on heart 70.

Once contoured and positioned as desired, suction may be applied at port22 of rigidifying bladder 14 by, for example, actuating valve 94,thereby stiffening ablation device 10 and maintaining the desiredcontour. The suction applied at port 22 is at a level which retardsbending and flexing of ablation device 10 under hand pressure. Dependingon the configuration of rigidifying bladder 14, such as the size and/ornumber of free-floating rigidifying structures 26, the level of suctionapplied at port 22 may range from, for example, about 80 mm Hg to about120 mm Hg. For many cardiac applications, the suction applied to port 22is such that stabilizer 10 is rigid to about 5 pounds to 10 pounds offorce.

Once suction is applied to both ports 16 and 22 as described above,ablation device 10 is attached and rigid, with heart 70 being in itsnormal cardiac anatomical position. The tissue of the heart 70 to whichablation device 10 is attached is stabilized. Ablation device 10 maythen be moved, thereby also moving heart 70 to a desired position toperform an ablative procedure.

External support structure 96 may include an articulated arm 98 with asocket 100, preferably a quick-release socket as shown, which isreleasably engageable with ball 58 of ablation device 10. Although aball-and-socket arrangement is used for the purposes of thisdescription, any complementary releasable fastening means may beimplemented. External support structure 96 may include a sternalretractor or a bed post 104 to which support arm 98 is attachable.Articulated support arm 98 may bendable under sufficient hand force.Alternatively, arm 98 may be substantially flexible for positioning andthen made rigid through the use of a tensioning cable mechanism.Although only one support arm 98 is shown, external support structure 96may include a second support arm attached to a second ball-and-postarrangement of ablation device 10. Once ablation device 10 is retainedby the external support structure 96, heart 70 is in a stable positionand the ablative procedure may be performed.

In various applications, the level of suction applied to port 16 toattach device 10 to heart 70 may vary. For example, about 100 mm Hg toabout 200 mm Hg may be applied to port 16 if a more secure attachment ofdevice 10 to heart 70 is desired and about 50 mm Hg to about 150 mm Hgmay be applied to port 16 if less secure attachment is desired.

During an ablation procedure, heart 70 may be repositioned as desired bybending or repositioning articulated arm 98. Alternatively, heart 70 maybe repositioned by releasing ablation device 10 from support arm 98,repositioning the device and heart as desired, and then reattaching thedevice to the arm. After the procedure, device 10 may be detached fromthe external support structure 96, allowing heart 70 to be returned tothe normal cardiac anatomical position. The suction may then bedisconnected from ports 16 and 22 by actuating valves 92 and 94.Accordingly, device 10 becomes flexible and unattached to the heart 70and may be removed. As some patients require more than one ablation, thesurgeon may then reapply device 10 to another portion of the heart 70 toperform another procedure.

In a commercial medical embodiment of tissue ablation device 10,bladders 12 and 14 may be made from substantially pneumaticallyimpervious and biocompatible material such as silicone or rubber.Alternatively, inner walls of bladders 12 and/or 14 may be made from oneor more porous materials, such as a mesh, to allow collapsing of one ormore walls, such as for rigidifying of rigidifying bladder 14.Rigidifying structure 26 may be made from silicone or epoxy material orfrom metal and may include free-floating metal or epoxy beads.Rigidifying structure 26 may also be made from nylon-reinforced siliconemounted to bladder 14. Retaining structure 54 may be made for stainlesssteel or other suitably rigid material such as nylon.

The overall dimensions of ablation device 10 configured for cardiac usemay be about 10 centimeters (cm) to about 15 cm in width and length andmay be about 0.5 cm to about 2 cm in thickness. Window 56 may be about0.5 cm to about 2 cm in width and at least about 3 cm in length.Openings 20 may be about 0.25 cm to about 1 cm in diameter. Ball 58 mayhave a diameter of about 0.5 cm to 1 cm and may project above a topsurface of stabilizer 10 by about 0.75 cm to about 3 cm.

With reference now to FIG. 11, and as mentioned above, many embodimentsof stabilization/ablation device 10 may be sufficiently flexible toallow introduction of device 10 into a patient or into another locationfor treatment through a trocar sheath 67. Trocar sheath 67 may compriseany laproscopic sheath, introducer sheath, or other similar minimallyinvasive device for introducing device 10 into a patient and/or to asurgical site in a minimally invasive manner. Device 10 may beintroduced by rolling, folding or otherwise adjusting the shape ofdevice 10 to fit within and through trocar sheath 67. Once delivered toa site for treatment, device 10 may then be released from sheath 67 forpositioning and treatment.

While the invention has been shown and described with reference tospecific embodiments thereof, those skilled in the art will understandthat alterations, modifications, additions and the like may be made tothe embodiments described above or to other embodiments withoutdeparting from the spirit and scope of the invention as defined by thefollowing claims. Accordingly, the present invention is not limited tothe embodiments shown and described above.

1. A method of stabilizing and ablating body tissue, the methodcomprising: contacting a tissue stabilizer having a non-rigid bladderwith the tissue; securing the tissue stabilizer to the tissue;rigidifying the bladder; and applying ablation energy to at least aportion of the tissue through the rigidfied bladder.
 2. A method as inclaim 1, wherein rigidifying the bladder comprises applying a vacuum tothe bladder, wherein the vacuum collapses the bladder to cause thebladder to rigidify.
 3. A method as in claim 2, wherein the vacuum isapplied to the tissue through at least one aperture in the bladder toenhance securing of the tissue stabilizer to the tissue.
 4. A method asin claim 3, wherein the vacuum is applied to the tissue through aseparate tissue securing bladder coupled with the rigidified bladder. 5.A method as in claim 3, wherein the vacuum is applied to the tissuethrough a tissue securing compartment in the rigidified bladder.
 6. Amethod as in claim 1, further comprising: engaging at least one engagingmember on the tissue stabilizer with at least one positioning device;and using the positioning device to position the tissue stabilizer in alocation for contacting the tissue.
 7. A method as in claim 6, whereinthe at least one engaging member comprises at least one post-like membercoupled with at least one rigid plate coupled with the bladder.
 8. Amethod as in claim 6, further comprising advancing the tissue stabilizerto a surgical site before the engaging step.
 9. A method as in claim 1,wherein the bladder further comprises: at least one port; a chamberwithin the bladder in communication with the port; and rigidifyingstructure disposed within the chamber, wherein the rigidifying structureis substantially flexible when no suction is applied at the port andsubstantially rigid when suction is applied at the port.
 10. A method asin claim 9, wherein rigidifying the bladder comprises applying a vacuumat the at least one port.
 11. A method as in claim 1, wherein applyingablation energy comprises ablating epicardial tissue adjacent at leastone pulmonary vein.
 12. A method as in claim 11, wherein the epicardialtissue comprises tissue at least partially encircling two pulmonaryveins.
 13. A method as in claim 1, wherein applying ablation energycomprises transmitting energy to the portion of the tissue, thetransmitted energy selected from the group consisting of radio frequencyenergy, ultrasound energy, microwave energy and cryogenic energy.
 14. Amethod as in claim 13, wherein transmitting energy comprisestransmitting radio frequency energy from at least one radio frequencycoil.
 15. A method as in claim 14, wherein the radio frequency coil isapproximately U-shaped so as to contact epicardial tissue adjacent atleast two pulmonary veins.
 16. A method as in claim 14, furthercomprising contacting a retractable portion of the radio frequency coilwith heart tissue encircling at least two pulmonary veins.
 17. A methodas in claim 14, wherein the radio frequency coil comprises multiplelinear radio frequency coils for ablating a linear pattern on theepicardial tissue.
 18. A method as in claim 13, wherein transmittingenergy comprises transmitting cryogenic energy from multiplethermoelectric chips.
 19. A method as in claim 1, further comprisingsensing, with the at least one sensor, an amount of ablation of thetissue.
 20. A method as in claim 19, wherein sensing comprises:transmitting a radio frequency signal across an area of ablated tissuewith a paired sensor; and receiving the radio frequency signal at asecond paired sensor.
 21. A method as in claim 1, further comprisingcooling the tissue stabilizer using a cooling member.
 22. A method as inclaim 21, wherein cooling the stabilizer comprises passing a coolingfluid through the cooling member.
 23. A method as in claim 1, furthercomprising delivering the tissue stabilizer through a minimally invasiveintroducer device to a location for contacting the tissue.